I'm just about to start my first attempts at wine making. We bought a gallon of organic, concentrated, concord grape juice to use for some other recipes and I have so much left over that I'm going to try making wine.

I have found some basic instructions on the web that seem quite simple and I'd like to find out if this will really produce a decent wine.

Without going into specific amounts, the recipe just calls for the reconstituted juice, yeast and sugar all placed into a recycled 3 liter wine bottle with a balloon on top which supposedly will tell me when the fermentation has stopped enough to bottle the wine.

That's what I was wondering. As @Larian said it must have something to do with the fermentation stopping.
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davidethellNov 26 '11 at 3:02

compared to making beer, the process for making wine is super simple. It's the waiting that is difficult.
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MattressNov 28 '11 at 19:37

The balloon is probably meant to be an airlock. I used to use a balloon as the airlock before I learned of better ways. I would cut a small hole in the top and it would let CO2 out, but no O2 in. When the balloon quit hissing as air left it, it was done fermenting.
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WulfhartMay 2 '12 at 23:29

As for recipes that use concord grapes for making wine, I have never used that grape (although it is the most commonly planted historically in North America). However, the all knowing google has a few suggestions. Sadly, very few of them start off with just the juice, and instead goes for the grapes themselves. I'm sure that there is a simple conversion though.

The Concord grape still remains the most popular grape sold in the United States with the majority of the vineyards in Washington and New York. The varietal has been used with great frequency in producing sweet Kosher wines such as Manischewitz and Mogen David. However, Concord grapes can also be used by the home winemaker to produce more complex vintages. Here are two recipes that are vastly different in style, yet both utilize Concord grapes.

Homemade Dry Concord Grape Wine Recipe

1 gallon water

10 lbs Concord grapes

1 1/2 cups sugar

1 teaspoon yeast nutrient

1 package wine yeast

Bring water and sugar to boil in a large pot. Separate grapes from stems and place in primary fermentation container. Crush grapes and pour water into container. Let cool until room temperature. Stir in yeast nutrient and yeast. Cover and let sit for 1 day. Ferment for 3 weeks stirring once a day. Strain through mesh bag into secondary fermentation container. Let rest for 1 month. Rack and let sit for 2 months. Rack into bottles and let rest for at least 9 months before serving.

Wash and de-stem grapes, discarding any less than perfect ones. Put in nylon mesh bag, tie securely, and vigorously crush grapes over primary, being sure to crush them all. Place bag of pulp in primary and add water, sugar, nutrient, and crushed Campden tablet. Stir well to dissolve sugar, cover securely with clean cloth and set aside. After 12 hours add pectic enzyme and recover. After additional 12 hours check specific gravity. If not at least 1.095, add sugar and stir until dissolved, then add yeast. Stir daily, squeeze the nylon bag to aid in juice extraction, and check the S.G. When S.G. reaches 1.030 (5-6 days), lightly but steadily press juice from bag. [Set bag aside in bowl to make a second wine (see third recipe below).] Siphon liquor off sediments into sterilized glass secondary and attach airlock. Check S.G. after 30 days. If 1.000 or lower, rack into clean secondary and reattach airlock. Rack again after 2 months and again after additional 2 months. Allow to clear, stabilize, sweeten if desired (1/2 to 3/4 cup sugar syrup per gallon), and rack again into sterilized bottles. Allow to age two years in bottle before tasting. Improves further with additional aging. [Adapted from Raymond Massaccesi's Winemaker's Recipe Handbook]

Concord Grape Wine (2)

12 lbs fresh Concord grapes

2 pts water

1-1/2 cups granulated sugar

1 tsp pectic enzyme

1 crushed Campden tablet

1 tsp yeast nutrient

wine yeast

Wash and de-stem grapes, discarding any less than perfect ones. Divide grapes into two nylon mesh bags, tie securely, and vigorously crush grapes over primary, being sure to crush them all. Place bags of pulp in primary and add sugar already dissolved in water, nutrient, and crushed Campden tablet. Cover securely with clean cloth and set aside. After 12 hours add pectic enzyme and recover. After additional 12 hours check specific gravity. If not at least 1.095, add sugar and stir until dissolved, then add yeast. Stir daily, squeezing the nylon bags to aid in juice extraction, and check the S.G. When S.G. reaches 1.030 (5-6 days), lightly but steadily press juice from bags. [Set bags aside in bowl to make a second wine (see third recipe below).] Siphon liquor off sediments into sterilized glass secondary and attach airlock. Check S.G. after 30 days. If 1.000 or lower, rack into clean secondary and reattach airlock. Rack again after 2 months and again after additional 2 months. Allow to clear, stabilize, sweeten (1-1/4 cup sugar syrup per gallon), and rack again into sterilized bottles. Allow to age two years in bottle before tasting. Improves further with additional aging. [Adapted from Raymond Massaccesi's Winemaker's Recipe Handbook]

Begin this wine as soon as practical after pulp is removed from previous use, as you will be using the yeast already present in the pulp (do not allow pulp to dry out). Mix all ingredients except pulp in primary, stir well to dissolve sugar, then add pulp still in nylon bag. S.G. may be lower than expected because of alcohol still trapped in pulp. Cover and ferment, stirring and squeezing bag daily, until S.G. drops to 1.010. Siphon liquor into secondary. Squeeze bag well to extract all juice possible. Add juice to secondary and fit airlock. Rack after 30 days, then every 2 months until wine is clear and no more yeast deposits form after 10 days. Stabilize, sweeten if desired, and siphon into bottles. Taste after two years.

Follow instructions for rehydrating yeast on package. While waiting on yeast, pour both cans of juice concentrate into a 1 gallon container and add sugar. add filtered water following directions on juice containers. When yeast is rehydrated, add to gallon container and shake vigorously to mix all ingredients.
Before I purchased airlocks, I used balloons rinsed and pre-stretched to fit the container top, held on with electrical tape for a tight seal.
Place container in dark closet, temperature around mid-70 degrees f.
When balloon starts to deflate (2.5-4 weeks), carefully pour into a clean, 1 gallon container, trying not to stir up sediment on bottom. Refrigerate and enjoy.
Ideally the wine should age 2 - 12 months, but I never could wait that long.
This yeast has always given me good results and was recommended by the wine shop owner as ideal for a beginner. Always follow good sanitation practices and you should be good to go.